Method and apparatus for cracking hydrocarbons



N. E. LOOMIS May l0, 1932.

METHOD AND APPARATUS FOR CRACKING HYDROCARBNS Filed March s, 1927 2Sheets-Sheet 1 I A mnwcoz "NATHMMLLLLooms @eww 'www May 1Q, 1932. N. E.LOoMls METHOD AND APPARATUS FOR CRACKING-HYDROCARBONS 2 Sheets-Sheet 2Filed March 3, 1927 Patented May 10, 1932 A i' UNrr'lzDV STATESNATHANIEL 4E. LOOMIS, OF v'WIEISTIEIIELD, NEW JERSEY, ASSIGNORTO-STANDABD'AOIL PATENT "o1-FICE DEVELOPMENT COMPANY, A CORPORATION OFDELAWARE METHOD AND APPARATUS FOR (TRACKING HYDBOGARBONB Application ledMarch 3, 1927. Serial No. 172,259.

This invention relates to improvements inv the cracking of petroleumoils and the like.

In a. preferred embodiment, the invention pSeries, and the vapors arefractionated and condensed. n

' The invention will be fully understood from the following description,read in con nection with the accompanyingy drawings, in which" ,v" 'y yFig. 1 isa diagrammatic side elevation of equipment suitable forpracticing the meth' od; and

Fig. 2 is a top plan view of the same equipment, partly broken away.

Referring to the drawings, reference numeral denotes a pipe arranged tosupply oil to be cracked to an elongated passageway or cracking coil 2mounted in a heating chamber 3. The coil may be ycomposed of about 1600ft. of 4 pipe, .preferably arranged for a successive counter-current andconcurrent P flow of oil with respect to hot gases, as shown. The coil 2dischargesl through pipe 4 into a heating conduit 5, immersed in a leadbath 6, or other means for maintaining a uniform lhigh temperature.4 Thelead bath or salt bath, such as that of sodium nitrite is set in afurnace 7 connected by a flue 8 to supply hot gases to the cracking coil2.

From the heating condult 5 the oil passes through a pipe 9 into thelower portion vof an v enlarged chamber or soaking drum 10.. This isheavily lagged or otherwise protected against any substantial loss ofheat.y The drum may be a heavy steel cylinder usually not larger thanabout 3 in diameter by 20 in height. However, smaller drums may be usedwith advantage, especially wherev a. considerable number are connectedin series.

Three 3 by 20 drums are ordinarily suiiicient for best results.

The oil emerges from' the top of the drum 10 through pipe 1l and entersa second heating conduit 12. It passes through this con- 55,'

duit and pipe 13 into a second drum 14, similar to that just described.From drum 14the oil emerges through pipe 15, which leads to a thirdheating conduit 16, and thence the oil Hows through pipe 17 to a thirddrum 18. Each of the drums is provided with a drawoil' line 19 near itsbottom, and valves 20 are arrangedin these draw-off lines.

Thecracked product is taken oi from the third drum 18 through pipe 21 tothe lowerA chamber of a bubble tower or other fractiony `having apressure control valve 27 and are condensed and collectedin any suitablemanner. Condensate formed in the. tower y is drawn' off through pipes 25and 28.' v

The pipes conveying the oil between the several cracking units arepreferably heatinsulated, but the bath 6 can be depended upon to make upthe heat losses from uninsulated ipes.-

preferred form is as follows: Kerosene, light gas oil, or other stocksuitable for cracking- The operatlon of the improved method in a atwhich incipient cracking takes place and v is in condition to be readilyvaporized when passed-into the reaction chamber or soaking drum 10. Thetemperature of the oil emerg-V ing from the cracking coil 2 ispreferably about 900"v F., and the pressure about 350- '400 lbs. persquare inch. Before entering' drum 10, the oil passes through theheating conduit 5, in which its temperature is raised about 50 F. It isdischarged through pipe -9 into the lower portion of drum 10 at about Ihave ,foundthat this increment of heat is necessary .for eiiici'ent'vapor phase cracking. lt cannot .be imparted to the oil in the crackingcoil 2 without serious danger of. hard coke formation in the coil tubes.'llhis danger is not met .in heating conduit 5. Thehigh rate of heattransfer between the molten 'metal or other fused material oi' the bath(i and the conduit makes it Vpossible to heat the oil very quickly tothe ,desiredvtemperature.

without substantial formation of coke.

-The time of hea-ting in the cracking coil.

may be one minute or less, andthe time oi' digestion may be from aboutone to five minutes in each drum. The' period of travel through conduit5 maybe onlyv a few seconds. These times may be considerably varied, de-

pending upon the stock, the amount of conversion desired, and otherfactors.

The oil passes'throughv pipe 11 and heating conduit 12 to the next drumof the series. It will be understood that the oil is mostly vaporized,but some liquid oil may be present. Any heat lost is supplied in theconduit 12 and the oil is raised to aneflicient conversion temperature,as above described.

Similarly, the oilpasses from the secondv drum through pipe 1,5 andheating coil 1G to the third drum 18. Pressure is released at valve 23and the products from drum 18 are.

delivered into the lower chamber of the bubble tower 22. The tower maybe operated under pressure, but lower than that in the cracking zones,for eiiample, 60 lbs.- per ksquare inch.

Gasoline and kerosene are taken oilthrough line 27 to condensing means,not show-n. Gas

oil collected in pan 25 is suitable for recycling through the system, orfor other uses. c

The invention is particularly adapted for vapor phase cracking.` Thedifficulty has been to maintain the temperature of the vapors at a pointto give a high cracking rate without y the use of extremely largecracking chambers .for prolonging the cracking period. By -heating asdescribed herein, the oil is eciently cracked.

900 F. under a. pressure of about 3594406' lbs. per square inch in anelongated passageway, further heating the oil to about 950 l?. in aconduit immersed in a molten bath, then digesting the oil vlargely invapor phase in a ythermally insulated Zone wherein some vloss of heatoccurs, passing the oil from the digestion zone through a heatingconduit in which n any loss of heat is made up, and then into anotherdigestion'stage, and recovering `the cracked product. l

2. ln the cracking of hydrocarbons inthe vapor phase, the method thatcomprises heating a stream of the hydrocarbons to an incipient vaporphasel cracking temperature under a pressure of S50-400 pounds persquare inch, further heating the hydrocarbons to an ecient vapor phasecracking temperature by passing them through an elongated pas sageimmersed in a fused bath, passing the heated hydrocarbons to a thermallyinsulated zone of relatively large cross-sectional vmy invention, Iaffix mysignature.

.NATHANIEL E. LOOMIS.

To preventbu-ilding up of liquid in the i drums, the heavy oilcollecting at their bottomsv may be drawn olf intermittently orcontinuously through the pipes 19. 'Theinvention is not restricted touse in .vapor phase operat1ons,v`and where liquid'phase, or semiliquidphase cracking is desired., the drums maybe allowed to become more orlless full of liquid.

Various changes may be made in the preerred method and equipmentdescribed, Within the scope'of the appended claims, in which it is myintention to claim all novelty inherent in the invention as broadly asthe prior` art permits. I claim:

1. The vimprovement in the process of cracking' relatively low-boilingpetroleum oi1s,..which comprises heating the oil to a cracking andvaporizing temperature about ico lois

